1. Field of the Invention
The present invention relates to a phase matching band-pass filter and, in particular, to a phase matching band-pass filter composed of devices having impedance changes following an exponential function in relation to frequency.
2. Description of the Related Art
The transceiver for use in baseband communication is provided with a low-pass filter to filter out the interferer while passing the original signal. Most communications are done over radio frequency carriers to avoid interference from each other, and the Radio Frequency (RF) transceiver of an RF system should use an RF band-pass filter that pass signals from a specific frequency band on which it operates.
In the current frequency allocation system in which the entire range of frequency spectrum is densely allocated for different usages, the load of the digital front end or converter (ADC) of the transceiver increases due to the other frequency band signals if the RF band-pass filter having High-Q value is not used. This means the load increase of the digital front end or ADC following the band-pass filter of the receiver. Also, most of conventional RF transceivers include the filters implemented Complementary Metal-Oxide Semiconductor (CMOS) process. In most cases, the RF band-pass filter having High-Q value is implemented with a Surface Acoustic Wave Filter (SAW Filter). However, the SAW filter which uses mechanical resonance is large in volume and impossible to integrate in the form of IC, resulting in increase of whole manufacturing cost of the RF transceiver.